1. Field of the Invention
The invention relates to an auto-lock mechanism, and more particularly to an auto-lock mechanism used in an image input/output device such as a scanner, a copier or a multi-function printer, wherein an upper cover can be automatically locked by the locking mechanism when the device is slantwise.
2. Prior Art
A typical image input/output device, such as a scanner, a copier or a multi-function printer, mainly includes a body and an upper cover, the upper cover can relatively be inserted into the body and opened from the body. Due to different devices having different sizes, the arrangement of various devices are not completely the same.
For example, in general, the scanner is placed on a table or a shelf. If the placement position of the scanner is flat, the scanner is not slantwise. However, when the scanner is placed on the shelf which may be reversed or shifted, or the scanner is placed on the table which may be shifted, the scanner which is placed on the table or the shelf becomes slantwise, and at this time the upper cover may be automatically opened from the body.
In addition, when the scanner is being moved, the upper cover may be automatically opened. Similarly, when the copier or the multi-function printer is being moved, the upper cover may be automatically opened due to the slantwise device.
In the above-mentioned image input/output device, two pivoting elements are disposed between the upper cover and the body, such that the upper cover can be opened or closed relative to the body. The pivoting elements may be disposed a hinge having a spring. With the reaction force of the spring of the hinge, the upper cover haves greater pressure to press on the body. However, when the upper cover is automatically opened, the reaction force of lifting the upper cover is larger than the restoring force of the spring. If the upper cover is automatically opened, the upper cover may hits the user and cause the user gets hurt, and what is more, if the force of automatically opened the upper cover is too great, the upper cover will be separated from the body and thus the image input/output device will be damaged.
Disposing at least one locking mechanism in the image input/output device can solve the problem of automatically opened the upper cover due to the slantwise of the device. A known design is to form a locking mechanism with a swingable element and a fixed element. The locking mechanism is disposed between the upper cover and the body. When the image input/output device is slantwise, the swingable element may swing to hook the fixing element and thus to keep the upper cover being fixed.
The above-mentioned design is disclosed that a movable element enables to approach a fixed element. Therefore, the stroke of locking is completed by the movable element, the total stroke and the time are longer, and the locking sensitivity is lower. Also, the locking mechanism cannot function as long as the swingable element is out of work. So, the reliability of the locking mechanism is not high.